Pakistan accused NATO on Saturday of killing up to 26 soldiers in air strikes, protesting in the strongest terms to the US and sealing its border to NATO supplies bound for Afghanistan. It was the deadliest NATO attack reported by Pakistan during the 10-year war in Afghanistan and looked set to inflame already extremely difficult US-Pakistani relations still reeling from the May killing of Osama bin Laden. A NATO spokesperson said 'close cooperation' with Pakistan would continue. Duration: 01:30